Dr. Phillip Vigneri spent hours preparing Dorothy Mark for what was about to happen in the room with leaded walls.

First, he put a long, skinny tube through a scope in Mark's nose and into a cancerous tumor in her windpipe. Next, on an X-ray, he mapped out the precise area he wanted to bombard with high doses of radiation.

Then, it was time to leave the 58-year-old Catasauqua woman alone in Sacred Heart Hospital's radiation therapy room with "the machine."

Called an automated remote afterloader, the machine looks more like an air pump at a gas station than a sophisticated piece of medical equipment.

Yet, as it ticks off the seconds, the afterloader pushes a tiny "seed" or pellet of high-dose radioactive material through the tubes placed inside the patient and into the heart of the tumor.

Still, the extra preparation is worth the effort, according to area cancer specialists. They say the therapy saves time and increases safety when obliterating cancerous tumors with radiation.

Patients spend less time in the hospital and receive less damage to healthy tissue than with other forms of radiation therapy, said Vigneri, director of radiation oncology at Sacred Heart, Allentown.

Many cancer patients can benefit from high-dose rate brachytherapy, as it is known. However, experts believe the treatment is best applied to certain stages of lung, esophageal, prostate, vaginal, uterine and breast cancers.

It will not replace traditional external radiation, they add, but gives cancer specialists another, more powerful weapon to aim at the enemy.

Dr. Victor Risch, chairman of radiation oncology at Lehigh Valley Hospital, said high-dose rate brachytherapy gives some patients options for better outcomes. For instance, a patient with a tumor in the tongue might otherwise lose his tongue to surgery or his jawbone to damaging effects of conventional radiation therapy. High-dose rate brachytherapy would not damage those body parts, he said.

"It's not the be-all, end-all answer, but it has its place," Risch said.

Like many lung cancer patients, Mark was not a candidate for surgery and had already received the maximum amount of external radiation.

High-dose rate brachytherapy gave doctors a way to continue shrinking her tumor.

Her dose -- 500 rads of iridium 192 -- would have taken 12 hours of standard radiation therapy, Vigneri said. With high-dose rate brachytherapy, it took two minutes.

Still in its infancy, though, the cancer treatment is not without risk. Four years ago, an 82-year-old Indiana County woman died from high-dose rate brachytherapy after a piece of radioactive material broke off inside her and staff members ignored equipment warnings, according to the U.S. Nuclear Regulatory Commission.

Also, a 1995 NRC report to Congress on "abnormal (nuclear) occurrences" cited a case in Irvine, Calif., in which a patient received high-dose rate brachytherapy to his healthy lung after a catheter had been improperly placed. It also revealed that a medical staff in Lawrenceville, Ga., exposed themselves to radioactive seeds they believed were "dummies," and an Army Medical Center in Ft. Lewis, Wash., gave four patients radiation doses differing by more than 10 percent from those prescribed because dose rate calculations were not independently checked.

Area cancer specialists said they have taken extra steps to ensure safety. However, questions remain about the long-term effects of quicker and higher doses of radiation.

"By jacking up the dose, you can give radiation therapy more rapidly and on an outpatient basis," Risch said. "The problem is the biological reaction is not equivalent" to the cellular reaction of equal amounts of external radiation.

Risch said radiation can cause immediate injury, such as reddened skin, that recovers in time. It is the long-term danger, including causing new cancer, they worry about most, he said.

Because high-dose rate brachytherapy is relatively new, he added, little is known about its long-term effects.

Brachytherapy, pronounced BRAKEY-therapy, began about 100 years ago and has been administered in various doses. Derived from the Greek word for close, the treatment first used radium, a highly radioactive metallic element which cost thousands of dollars to produce and caused finger loss among handlers.

Safety has improved with the artificial production of radioactive isotopes, such as iridium-192 and caesium-137, and the invention of the remote-controlled afterloader.

Afterloaders eliminate the need for doctors, nurses or technicians to touch the radioactive pellet, which is welded to a wire.